Correlation of Plant Condensed Tannin and Nitrogen Concentrations to White-Tailed Deer Browse Preferences in the Cross Timbers
Keywords:condensed tannins, crude protein, forage preferences, white-tailed deer
Chemical plant defenses such as condensed tannins (CT) have the potential to reduce insect herbivory. Condensed tannins sometimes also reduce ruminant herbivory as a result of decreased palatability and nutrient availability in gastro-intestinal systems. However, when consumed as 1-3% of diets, CT can be beneficial to ruminants as anthelminthics and by binding to plant proteins to enhance rumen-bypass protein. Given that plant nitrogen and CT are important ruminant nutritional factors, this study was designed to investigate correlations between deer browse preference and crude protein (CP) and/or CT concentration. In this study we collected 56 preferred warm-season white-tailed deer browse species within the cross-timbers region of Texas and analyzed for CT and CP concentrations. Plant CT varied from 78.4% to 0.5% (dry matter basis, Schinopsis balansae CT standard) and CP ranged from 23.8% to 5.0%. However, there was no correlation between plant CT or CP concentrations and published deer preference. Our study suggests that, while CT and CP may be important components of the white-tailed deer diet, preference is not based solely on CT or CP concentrations. Further research is needed to determine if plant maturity or surrounding vegetation confound correlations between white-tailed deer feed preferences and CT or CP in those selectively browsed plants. Use of a self-standard from each plant species to measure CT of that species may also change correlations.